Amyloid β-protein(Aβ) deposition in the brain is directly responsible for neuronal mitochondrial damage of Alzheimer's disease(AD) patients. Mitophagy, which removes damaged mitochondria, is a vital mode of neuron protection. Ginsenoside Rg_1(Rg_1), with neuroprotective effect, has displayed promising potential for AD treatment. However, the mechanism underlying the neuroprotective effect of Rg_1 has not been fully elucidated. The present study investigated the effects of ginsenoside Rg_(1 )on the autophagy of PC12 cells injured by Aβ_(25-35) to gain insight into the neuroprotective mechanism of Rg_1. The autophagy inducer rapamycin and the autophagy inhi-bitor chloroquine were used to verify the correlation between the neuroprotective effect of Rg_1 and autophagy. The results showed that Rg_1 enhanced the viability and increased the mitochondrial membrane potential of Aβ-injured PC12 cells, while these changes were blocked by chloroquine. Furthermore, Rg_(1 )treatment increased the LC3Ⅱ/Ⅰ protein ratio, promoted the depletion of p62 protein, up-regulated the protein levels of PINK1 and parkin, and reduced the amount of autophagy adaptor OPTN, which indicated the enhancement of autophagy. After the silencing of PINK1, a key regulatory site of mitophagy, Rg_1 could not increase the expression of PINK1 and parkin or the amount of NDP52, whereas it can still increase the LC3Ⅱ/Ⅰ protein ratio and promote the depletion of OPTN protein which indicated the enhancement of autophagy. Collectively, the results of this study imply that Rg_1 can promote autophagy of PC12 cells injured by Aβ, and may reduce Aβ-induced mitochondrial damage by promoting PINK1-dependent mitophagy, which may be one of the key mechanisms of its neuroprotective effect.
Amyloid beta-Peptides/toxicity* ; Animals ; Ginsenosides/pharmacology* ; Humans ; Mitophagy/physiology* ; PC12 Cells ; Protein Kinases/metabolism* ; Rats ; Ubiquitin-Protein Ligases/metabolism*

OBJECTIVETo explore the biological activity of recombinant human single-chain antibody against amyloid beta peptide in vitro.

METHODSHuman single-chain antibody against amyloid beta peptide was obtained from recombinant bacteria. The antigen-binding activity of this antibody was measured by enzyme-linked immunosorbent assay (ELISA) and competitive ELISA. Human neuroblastoma SH-SY5Y cells were used as cell models to test the protective role of human single-chain antibody against amyloid beta peptide.

RESULTSRecombinant human single-chain antibody was mainly located in the insoluble inclusion bodies of bacteria. The antibody was dissolved by urea and purified by metal affinity chromatography as active form to bind synthetic amyloid beta peptide 40 or amyloid beta peptide 42. The improvement of the survival rates of human neuroblastoma cells was significantly superior in amyloid peptide 42 plus equimolar antibody group than in amyloid peptide 42 group (P < 0.05), and was significantly superior in the amyloid peptide 40 plus equimolar antibody group than in amyloid peptide 40 group (P < 0.01).

CONCLUSIONThe recombinant human single-chain antibody against beta amyloid peptide 40 from E. coli can partially inhibit the neurotoxicity effect of amyloid beta peptide in vitro.

Amyloid beta-Peptides ; immunology ; metabolism ; toxicity ; Cell Line, Tumor ; Cell Survival ; drug effects ; Humans ; Peptide Fragments ; metabolism ; toxicity ; Protein Binding ; Recombinant Proteins ; pharmacology ; Single-Chain Antibodies ; pharmacology

To explore the relationship between beta-amyloid (A beta) and the pathogenesis of Alzheimer disease (AD), after injection of beta-amyloid into the rat brain, the apoptosis of nerve cells and acetylcholine (Ach) content in rat hippocampus were examined by employing TUNEL technique and base hydroxylamine colorimetry respectively. The influence of age and glucocorticoid on the neurotoxic effect of A beta was also analyzed. A beta peptide could strongly induce the apoptosis of neurons in hippocampus, cortex and striate body (P < 0.05 or P < 0.01). In addition, the senility and glucocorticoid pre-treatment could enhance the toxic effect of A beta (P < 0.05 or P < 0.01). It is concluded that A beta may play an important role in the pathogenesis of Alzheimer disease via its induction of apoptosis of neurons and by decreasing the content of the Ach.
Acetylcholine/metabolism ; Aging ; Alzheimer Disease/etiology ; Amyloid beta-Protein/*toxicity ; Apoptosis/*drug effects ; Dexamethasone/*pharmacology ; Drug Synergism ; Hippocampus/metabolism ; Hippocampus/*pathology ; Injections, Intraventricular ; Neurons/pathology ; Rats, Wistar

OBJECTIVETo investigate the changes of p38MAPK expression in a rat model of Alzheimer disease (AD).

METHODSSeventy-two adult SD rats were randomized equally into 4 groups, and a single-dose injection of Abeta25-35 (dementia group), normal saline (saline group), SB203580 (inhibitor group), or DMSO (inhibitor control group) was administered into the lateral cerebral ventricle. Y-maze tast was performed to evaluate the behavioral changes of the rats after the injections, and on days 4, 7 and 14 after the injection, p38MAPK expression in the hippocampal CA1 area was measured by means of immunohistochemistry.

RESULTSOn days 7 and 14 following Abeta25-35 injection, the training times, error number and total reaction time were significantly higher in dementia group than in saline group (P<0.05), but all these indices were significantly lowered in the inhibitor group as compared with the dementia group (P<0.05). Immunohistochemistry revealed obvious p38 expression in the dementia group 4 days after Abeta25-35 injection, which increased significantly with the passage of time (P<0.01). The gray scale in the inhibitor group was significantly higher than that in the dementia group (P<0.01).

CONCLUSIONp38MAPK activation in the hippocampal CA1 area is an event that persists during the entire course of Abeta25-35-induced AD in rats, and the inhibitor SB203580 prevents p38MAPK expression and improves the learning and memory abilities of the rats.

Alzheimer Disease ; chemically induced ; enzymology ; metabolism ; Amyloid beta-Peptides ; administration & dosage ; toxicity ; Animals ; Hippocampus ; drug effects ; enzymology ; Immunohistochemistry ; Male ; Maze Learning ; drug effects ; Peptide Fragments ; administration & dosage ; toxicity ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; p38 Mitogen-Activated Protein Kinases ; biosynthesis

Amyloid beta (Abeta) neurotoxicity is believed to play a critical role in the pathogenesis of Alzheimer's disease (AD) mainly because of its deposition in AD brain and its neuronal toxicity. However, there have been discrepancies in Abeta-induced cytotoxicity studies, depending on the assay methods. Comparative analysis of Abeta42-induced in vitro cytotoxicity might be useful to elucidate the etiological role of Abeta in the pathogenesis of AD. In this study, MTT, CCK-8, calcein-AM/EthD-1 assays as well as thorough microscopic examinations were comparatively performed after Abeta42 treatment in a neuronal precursor cells (NT2) and a somatic cells (EcR293). Extensive formation of vacuoles was observed at the very early stage of Abeta42 treatment in both cells. Early observation of Abeta42 toxicity as seen in vacuole formation was also shown in MTT assay, but not in CCK-8 and calcein-AM/EthD-1 assays. In addition, Abeta42 treatment dramatically accelerated MTT formazan exocytosis, implying its effect on the extensive formation of cytoplasmic vacuoles. Abeta42 seems to cause indirect inhibition on the intracellular MTT reduction as well as vacuole formation and exocytosis enhancement. Following the acute cellular dysfunction induced by Abeta42, the prolonged treatment of micromolar concentration of Abeta42 resulted in slight inhibition on redox and esterase activity. The early Abeta42-induced vacuolated morphology and later chronic cytotoxic effect in neuronal cell might be linked to the chronic neurodegeneration caused by the accumulation of Abeta42 in AD patients' brain.
Amyloid beta-Protein/*toxicity ; Animals ; Cell Death/drug effects ; Cell Line ; Dose-Response Relationship, Drug ; Exocytosis/*drug effects ; Formazans ; Neurons/*drug effects/metabolism/*pathology ; Peptide Fragments/*toxicity ; Research Support, Non-U.S. Gov't ; Tetrazolium Salts ; Time Factors ; Vacuoles/*drug effects

OBJECTIVESTo investigate the neuroprotective function of alpha7 nicotinic receptor (nAChR) and its roles in the pathogenesis of Alzheimer's disease (AD).

METHODSpecific RNA interference to alpha7 nAChR mRNA expression was performed by gene specific small interference RNA (siRNA). SH-SY5Y cells were transfected with the siRNA or treated with 20 micromol/L 3-[2, 4-dimethoxybenzylidene] anabaseine (DMXB), an alpha7 nAChR agonist. After 48 hrs culture, levels of alpha7 nAChR mRNA and protein were monitored by RT-PCR and Western blotting, respectively. In the second experiment, SH-SYSY cells treated with siRNA or DMXB were exposed to 1 micromol/L Abeta(25-35), followed by protein analysis of alpha-form of secreted beta-amyloid precursor peptide (alphaAPPs), and total APP was assayed by Western blotting. In addition, lipid peroxidation and MTT [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] reduction were measured by spectrophotometry.

RESULTIn RNA interference group, as compared with controls, alpha7 nAChR mRNA and protein levels were decreased with inhibitory efficiency by 80% and 69%, respectively, along with a decrease in protein levels of alphaAPP and reduction of MTT. However the product of lipid peroxidation was increased. There was an enhanced gene inhibition of alpha7 nAChR by Abeta. While cells treated with DMXB, the alpha7 nAChR protein was increased by 23% as compared with that of the control, along with decrease of alphaAPP and ERK 1/2 at the protein level. The enhanced expression of alpha7 nAChR reduced the neurotoxic effects resulted from Abeta.

CONCLUSIONThe findings indicate that alpha7 nAChR may play a significant neuroprotective role by enhancing cleavage of APP, improving antioxidant defenses and limiting the toxicity of Abeta, which has been implied in the pathogenesis of AD.

Acetylcholine ; pharmacology ; Alzheimer Disease ; pathology ; physiopathology ; Amyloid beta-Peptides ; metabolism ; toxicity ; Amyloid beta-Protein Precursor ; pharmacology ; Cells, Cultured ; Humans ; Lipid Peroxidation ; Neurons ; drug effects ; pathology ; Neuroprotective Agents ; pharmacology ; Nicotinic Agonists ; pharmacology ; Protease Nexins ; RNA Interference ; RNA, Messenger ; drug effects ; metabolism ; RNA, Small Interfering ; pharmacology ; Receptors, Cell Surface ; Receptors, Nicotinic ; metabolism ; physiology ; alpha7 Nicotinic Acetylcholine Receptor

OBJECTIVETo observe the effects of hippocampal Abeta42 deposition on the expression of inflammatory cytokines and phosphorylated MAPK signal molecules as well as the intervention of AD by total glucosides of paeony (TGP).

METHOD12 week-old female SD rats were stereotactic injected one-time with a fibrillar Abeta42 positioning hippocampus to replicate AD pathology model and interfered with TGP. The expression of inflammatory cytokines and phosphorylated MAPK pathway signaling molecules were observed by immunohistochemistry (SABC), and SABC images were analyzed by image analysis software.

RESULTCompared with the control group, the IL-1beta, IL-6 and p-p38, p-JNK, p-MEK3/6 positive stained areas of AD pathology model group increased and their staining intensity decreased (the protein expression quantity inversely proportional to the staining intensity), while the IL-1beta, IL-6 and p-p38, p-JNK, p-MEK3/6 positive stained areas of the treatment groups decreased and their staining intensity increased compared with AD pathology model group.

CONCLUSIONAbeta42 deposition in hippocampus can induce the brain inflammation and the over-expression of IL-1beta, IL-6 and p-p38, p-JNK, p-MEK3/6. Inhibiting the over-expression of inflammatory cytokines and phosphorylated MAPK signaling molecules may be a major antagonistic mechanism of TGP against AD.

Alzheimer Disease ; drug therapy ; Amyloid beta-Peptides ; metabolism ; toxicity ; Animals ; Cytokines ; analysis ; Female ; Glucosides ; pharmacology ; therapeutic use ; Hippocampus ; metabolism ; JNK Mitogen-Activated Protein Kinases ; metabolism ; MAP Kinase Signaling System ; drug effects ; Mitogen-Activated Protein Kinases ; metabolism ; Paeonia ; chemistry ; Peptide Fragments ; metabolism ; toxicity ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo explore the expression of GSK-3beta, CDK-5 and PP2A and the regulation of them by Abeta(25-35) and ginsenoside Rb1 after neural stem cells (NSCs) are transformed into neurons.

METHODSTo culture NSCs from the dentate gyrus of newborn rats(24 h) hippocampus in vitro. NSCs of the third passage were induced towards neurons; the expressions of GSK-3beta(pTyr279,216), PP2A and the regulation of them by Abeta(25-35) and ginsenoside Rb1 were tested by the immunofluorescence cytochemical staining after NSCs had been induced for one week; The expressions of GSK-3beta, CDK-5, PP2A and the regulation of them by Abeta(25-35) and ginsenoside Rb1 were detected with RT-PCR.

RESULTSImmunofluorescence cytochemisty showed that neural cells from NSCs which had been differentiated after one week could express GSK-3j (pTyr279,216)and PP2A. Abeta(25-35) could enhance the expression of GSK-3beta(pTyr279,216), meanwhile it also restrained the expression of PP2A. Moreover ginsenoside Rb1 could reverse the affect of Abeta(25-35). RT-PCR found that neural stem cells which had been differentiated after one week could express GSK-3beta, CDK-5, PP2A . The expression of GSK-3beta and CDK-5 rose up and the expression of PP2A weakened when they were treated by Abeta(25-35). However, the effect of Abeta(25-35) was restrained when they were pretreated by ginsenoside Rb1.

CONCLUSIONThese observations indicated that NSCs which were cultured and induced in vitro can express GSK-3beta, CDK-5 and PP2A; moreover Abeta(25-35) and ginsenoside Rb1 can regulate the expressions of GSK-3beta, CDK-5 and PP2A. It hints that cells which differentiated from neural stem cells in vitro have protein phosphorylation regulation system of normal cells.

Amyloid beta-Peptides ; toxicity ; Animals ; Animals, Newborn ; Cell Differentiation ; Cells, Cultured ; Cyclin-Dependent Kinase 5 ; metabolism ; Female ; Ginsenosides ; pharmacology ; Glycogen Synthase Kinase 3 ; metabolism ; Glycogen Synthase Kinase 3 beta ; Hippocampus ; cytology ; Male ; Neural Stem Cells ; cytology ; metabolism ; Peptide Fragments ; toxicity ; Protein Phosphatase 2 ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo assess the neuroprotective effects of ginsenoside Rg1 against &beta;-amyloid peptide (A&beta;(25-35))-induced apoptosis in primarily cultured rat cortical neurons.

METHODSPrimarily cultured cortical neurons were obtained from embryonic (E18d) rat fetus and maintained in neurobasal medium for 7d. Primary neurons pretreated with 1 μmol/L, 10 μmol/L or 20 μmol/L Rg1 for 24 h were challenged with 10 μmol/L A&beta;(25-35) for 72 h. Morphological changes of neurons were evaluated; mitochondrial membrane potential (ΔΨm) was measured; with JC-1 staining and the expression of neural apoptosis-related proteins was detected by Western blot analysis.

RESULTSExposure to A&beta;(25-35) for 72 h caused serious neural cell insults. A pretreatment with Rg1 significantly reduced A&beta;(25-35)induced cell death in a dose-dependent manner, with a maximal effect (-90%) obtained at 20 μmol/L. The JC-1 staining results demonstrated the loss of ΔΨm after A&beta;(25-35) treatment, while Rg1 maintained the normal level of ΔΨm. A series of mitochondrion-mediated apoptotic events happened after A&beta;(25-35) treatment, such as decrease of Bcl-2/Bax, release of cytochrome C and activation of caspase 9 and caspase 3, which were all blocked by Rg1 pretreatment. Both estrogen receptor (ER) antagonist ICI182, 780 and glucocorticoid receptor (GR) antagonist RU486 blocked the antiapoptotic effects of Rg1.

CONCLUSIONGinsenoside Rg1 protects primary cultured rat cortical neurons from A&beta;(25-35)-induced injury, which may be associated with mitochondrion-mediated antiapoptosis pathway.

Amyloid beta-Peptides ; toxicity ; Animals ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Caspase 9 ; metabolism ; Cells, Cultured ; Cerebral Cortex ; drug effects ; metabolism ; pathology ; Ginsenosides ; pharmacology ; Membrane Potential, Mitochondrial ; drug effects ; Mitochondria ; drug effects ; metabolism ; physiology ; Neurons ; drug effects ; metabolism ; pathology ; Peptide Fragments ; toxicity ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo investigate the effect and mechanism of meloxicam on the inflammatory reaction induced by beta amyloid protein (AB) in Alzheimer's disease (AD) rats.

METHODSThe rat model was established by microinjection of Abeta(1-40) into hippocampus. The expression of NF-kappaB p65 and glial fibrillary acidic protein (GFAP) in hippocampus were detected by immunohistochemistry. The content of GFAP in cortex was tested by Western-blot. The content of TNF-alpha in cortex was tested by ELISA. The expression of IL-1beta mRNA was tested by RT-PCR.

RESULTSThe expression of NF-kappaB p65, GFAP and TNF-alpha as well as IL-1beta mRNA were decreased by meloxicam.

CONCLUSIONMeloxicam can reduce the proliferation of astrocyte by decreasing the expression of GFAP in AD model rat's hippocampus and cortex. And the depression of NF-kappaB p65 may significantly decrease the expression of TNF-alpha1 and IL-1beta to lessen the inflammatory reaction in cerebral tissue.

Alzheimer Disease ; chemically induced ; drug therapy ; pathology ; Amyloid beta-Peptides ; toxicity ; Animals ; Cerebral Cortex ; metabolism ; pathology ; Glial Fibrillary Acidic Protein ; metabolism ; Inflammation ; prevention & control ; Interleukin-1beta ; metabolism ; Male ; Peptide Fragments ; toxicity ; Rats ; Rats, Sprague-Dawley ; Thiazines ; pharmacology ; therapeutic use ; Thiazoles ; pharmacology ; therapeutic use ; Transcription Factor RelA ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism